Friction plug welding is a well known technique whereby through holes in component parts (especially metal parts) may be filled with a similar material so as to retain substantially the mechanical characteristics of the part. For example, in U.S. Patent Application Publication 2006/0131364 published on Jun. 22, 2006 (the entire content of which is expressly incorporated hereinto by reference), a friction plug welding technique is disclosed which employs a restraint part which defines a blind cavity axially aligned with the hole to be plugged so as to receive a terminal end of the male plug during the welding operation. The bottom surface of the cavity serves as a limit stop for the maleF plug and receives a flash flow of weld mix material exiting the hole at the back face of the component part that is generated during welding. Excessive flash flow may also be generated at the front face of the component part. Such flash flow can be undesirable as it may lead to annular weld defects at the front and back faces of the component part.
It would therefore be desirable if friction plug welding techniques could be provided which minimize (if not eliminate entirely) such annular weld defects. It is towards providing such solutions that the present invention is directed.
A friction plug welding methods and systems are provided so as to plug a hole extending through a component part from front and back faces thereof. In some embodiments a sacrificial plate having an opening therethrough will be positioned against the back face of the component part so that the opening is coaxially aligned with the hole to be plugged. Upon advancing a male plug of a plug rod into the hole under friction plug welding conditions, a friction weld region will therefore be formed between the male plug and defining surfaces of both the hole extending through the component part and the opening extending through the sacrificial plate.
In certain advantageous embodiments, a plug rod is provided with an annular shoulder flange which defines a plane parallel to the front face of the component part. Thus, advancement of the male plug of the plug rod into the hole will cause the annular shoulder flange to be adjacent to a corresponding region of the front face surrounding the hole. As such, flash flow from the friction welding will be displaced laterally of the hole. The male plug is preferably tapered, that is having a frustroconical shape. An annular arcuate surface may also be provided which joins the male plug to the shoulder flange.
According to some embodiments, the sacrificial plate will be positioned against the back face of the component part with a restraint part. The restraint part may be provided with a recessed region which is open adjacent to the back face of the component part and which is sized and configured to receive the sacrificial plate therein. The restraint part may also be provided with a space (e.g., a through hole or recessed cavity) of sufficient depth for receiving a terminal end portion of the male plug therein during the friction plug welding.
It is usually preferred that the male plug and the sacrificial plate are each formed of the same or a compatibly similar material as that of the component part.
Following a friction plug welding operation, the plug rod and the sacrificial plate may be removed from the component part along respective planes coincident with the front and back faces thereof. When removed, therefore, a segment of the male plug will be positioned as a plug within the hole and is welded to the component part. A new hole may thus be formed through the remaining segment of the male plug.
These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.